A conventional optical path adjusting device for a magneto-optical disk device provided with an optical system holding portion and a light source holding portion is known (For example, refer to Patent Document 1).
In Patent Document 1, an optical path adjusting device for a magneto-optical disk device is disclosed that comprises a semiconductor laser, a first fixing member (light source holding portion) for holding the semiconductor laser, a collimator lens, and a second fixing member (optical system holding portion) for holding the collimator lens. In this optical path adjusting device, the first fixing member and the second fixing member are fixed by a bolt with the first fixing member positioned in relation to the second fixing member (position adjusting for optical path adjusting).